[en] The aim of the Sector 3 research programme into underground disposal of radioactive wastes is to support the Inspectorate in discharging its statutory responsibilities under RSA60. The research projects in Sector 3 are focused on the assessment of the deep underground disposal facility proposed by UK Nirex Ltd (Nirex). This facility is being designed by Nirex to accept low and intermediate level radioactive wastes. It may be sited at Sellafield in Cumbria or at Dounreay in northern Scotland. Nirex will be required to submit an application for authorisation under RSA60 for the disposal facility. However, prior to this a public inquiry will be held under the Town and Country Planning Act, which will consider an application to further explore the nominated potential deep disposal site. The principal purpose of the research programme in Sector 3 is to support the assessment of the Nirex application. A secondary objective is to provide HMIP with a sound scientific and technical basis for its role in the prospective planning public inquiry. This will require HMIP to give a provisional view on the Nirex safety case presented in its preliminary submissions. (Author)